Packing tubes having a top part including a continous axial neck channel and lateral access passages opening into it are known. The tube neck is prefabricated and inserted into the top of the tube so that it projects into the body thereof. The access passages and the neck channel communicate with the tube interior and serve to form a strand having parallel strips at its surface. If the material near the access passages has a different colour from the rest of the material, the strips can be coloured.
Since the access passages in the neck form external undercut portions, the known moulding tools have an inner part forming the neck channel and also have a multiple outer part, e.g. with radially movable jaws, so as to release the undercut portions when the tube neck is released from the injection mould.
In addition to the cost of manufacturing these tools, the cost of operating them is considerable. They also have a short working life, owing to the relatively rapid wear on the jaw parts. The necks are therefore expensive to produce.